Untitled Quiz

Chemical Reactions

• Chemical reactions are processes that transform one or more substances into one or more new substances.
• Substances initially present are reactants, with new substances formed as products. Atoms are neither created nor destroyed.
• Chemical reactions are confirmed by observable changes, such as color change, energy exchange (heat or light), gas production, precipitate formation, and property change.

Evidence of a Chemical Reaction

• A chemical change always produces matter differing from the initial form.
• Examples include: rust forming, combustion, cooking, digestion, and decomposition.

The Chemical Equation

• Reactants and products are identified using chemical formulas.
• Reactants are written before the arrow "→", which separates them from the products written to the right.
• Subscripts in formulas indicate the ratio of atoms in a molecule.
• Coefficients in front of formulas indicate the number of molecules in a reaction.

How to Write Balanced Chemical Equations

• Coefficients, not subscripts, are adjusted to balance equations.
• The law of conservation of mass dictates that the number and type of atoms on both sides of a balanced equation must be equal.
• A balanced chemical equation displays a precise ratio of reactants and products involved in the reaction.
• Simple steps to balance an equation include: identifying the most complex molecule, adjusting coefficients for the elements in only that molecule, and finishing with adjusting coefficients for the remaining elements.

Aqueous Solutions and Solubility- Compounds Dissolved in Water

• Electrolytes are substances that dissolve in water to produce ions, with strong electrolytes dissolving completely, and weak electrolytes partially.
• Nonelectrolytes do not produce ions when dissolved in water.
• Conductivity is measured by the dissolved ions' concentration, the electrical current through electrodes in the solution, influencing the bulb's brightness.
• Ions and polar molecules, like water, are attracted by ion-dipole interactions, facilitating dissolution.

Precipitation Reactions

• When two solutions containing soluble ionic compounds mix, an insoluble product (precipitate) can form, often with color change.
• Predicting reactions (or lack thereof) can be determined by examining possible products and their solubility rules.

Writing Chemical Equations in Solution

• Molecular equations represent the overall reaction, including the states of reactants and products (solid, liquid, gas, aqueous).
• Complete ionic equations show all ions present in the solution.
• Spectator ions, ions that do not participate, are omitted in the net ionic equation, focusing on the reacting species.

Acid-Base and Gas Evolution Reactions

• Reactions between acids and bases (neutralization reactions) produce water and salt (ionic compound).
• Gas evolution reactions involve the production of a gaseous product, often when acids react with carbonates or bicarbonates.
• Examples include reactions creating CO2, H2S, or other gases.

Oxidation-Reduction Reactions

• Oxidation involves a loss of electrons or a gain of oxygen; reduction involves a gain of electrons or a loss of oxygen.
• Redox reactions involve the transfer of electrons from one reactant to another.
• Oxidation numbers are used to track electrons during redox reactions.

Classifying Chemical Reactions

• Chemical reactions generally fit into five types including acid-base, combination (synthesis), decomposition, single replacement, and double replacement.

The Activity Series- Predicting Spontaneous Redox Reactions

• The activity series ranks elements based on their tendency to lose or gain electrons in redox reactions, predicting spontaneous single displacement reactions (metal replacement).